1. Field of the Invention
This invention relates to a method and apparatus for applying a bonding agent such as an orthodontic cement or adhesive to an inner surface of an orthodontic band prior to installation of the band on a patient's tooth.
2. Description of the Related Art
Orthodontic treatment involves movement of malpositioned teeth to orthodontically correct locations for improved occlusion and appearance. One type of orthodontic treatment includes the use of tiny, slotted brackets that are connected to the patient's teeth, along with an archwire that is fitted into the slot of each bracket. The archwire forms a track to guide movement of the teeth to desired positions. In this type of treatment, the ends of the archwires are often captured in small appliances known as buccal tubes that are secured to the patient's molar teeth.
In many instances, orthodontic brackets are fixed to the patient's teeth using a technique known as direct bonding, wherein a small amount of adhesive is used to secure the base of the bracket directly to the tooth enamel. However, in some instances directly bonded brackets are not used. For example, one or more of the patient's teeth may be covered with a porcelain crown or have a front surface with a restorative material that prevents a strong bond to a bracket with the adhesives that the practitioner prefers to use. In other instances, the practitioner may simply prefer to use bands for all of the teeth receiving a bracket in accordance with his or her treatment philosophy.
Additionally, it is common practice to avoid bonding brackets or buccal tubes directly to the patient's molar teeth. The molar teeth have relatively large roots and are often used as an anchor for moving the other, smaller teeth to desired positions along the dental arch. As a consequence, the brackets and buccal tubes connected to the patient's molar teeth often are subjected to relatively large forces that may exceed the bond strength exhibited by brackets and buccal tubes that are directly bonded to the molar teeth.
Brackets and buccal tubes that spontaneously debond from the associated teeth during the course of treatment represent a substantial nuisance, since the progress of treatment is then interrupted. At that time, the patient should return to the orthodontist so that the brackets and/or buccal tubes can be rebonded, or replaced and rebonded as necessary. This procedure represents a waste of time and expense for both the orthodontist as well as for the patient, and is preferably avoided if at all possible.
As a result, orthodontic bands are often used by practitioners for at least some of the teeth of each patient. An orthodontic band is a thin, annular-shaped strip of metal alloy such as stainless steel that encircles the patient's tooth. The band serves as a secure mounting platform for a bracket or buccal tube, which is conventionally welded or brazed to the band before installation of the band on the patient's tooth.
However, it is important that the selected band fit tightly on the patient's tooth so that the band does not become loose or detached from the tooth during the course of treatment. Since teeth vary widely in size and configuration, the practitioner will often retain a wide variety of bands on hand in order to ensure that a band that properly fits is available when needed. Typically, the practitioner will trial fit two or three differently-sized bands on the tooth and then select the band that fits the best.
Once the band has been selected and the appliance (such as a bracket or buccal tube) is secured to the band, the band is mounted on the patient's designated tooth. Generally, a small layer or ribbon of orthodontic adhesive or cement is applied to the entire inner peripheral surface of the band prior to placing the band on the tooth. The adhesive or cement serves two functions: (1) to increase the strength of the bond between the band and the tooth; and (2) to fill any small gaps or voids between the band and the tooth in order to eliminate space that might otherwise collect food or other debris and facilitate formation of caries.
Conventional bonding agents such as adhesives and cements that are used for orthodontic banding are often supplied by the manufacturer in a bulk syringe for use with a multiple number of bands and a multiple number of patients. However, such syringes should not be used for directly applying the bonding agent to the inner surface of the band if the band has been previously used for a trial fit in the patients mouth, since there is a possibility that cross-contamination may occur when the same syringe is used for a band of a subsequent patient. As a result, it is recommended to dispense the bonding agent of conventional syringes onto a mixing pad, and then use a hand instrument such as a spatula to transfer the bonding agent from the pad to the inner surface of the band.
Unfortunately, the procedure for applying bonding agent to bands as mentioned above is not entirely satisfactory. For one thing, it is rather time consuming to first deposit the bonding agent from the syringe onto the pad and then transfer the bonding agent from the pad to the band. Moreover, once the inner surface of each band has received a sufficient amount of bonding agent, any bonding agent remaining on the pad is considered waste and is discarded.